1. Field of the Invention
The present invention relates to a system for automated toll collection which automatically tracks charges wherever fees are charged for entering predetermined geographical locations. More specifically, the invention relates to an automated toll collection system which uses Global Positioning System ("GPS") technology to lower costs.
2. Related Art
Specifications for automatic toll collection systems currently under development call for the use of radio frequency ("RF") devices. These systems typically consist of a large toll plan containing a large metal structure spanning all lanes of traffic. A radio frequency ("RF") reader is installed over each lane of traffic and supported by the large metal structure. The RF reader is linked to a computer which collects the raw data and sorts incoming data from the multiple lanes of traffic. The computer communicates with a central processing area where additional computers perform accounting operations. It should be noted that the RF reader is generally hardwired to the computer and is thus susceptible to lightning.
As currently contemplated by designers, a vehicle is equipped with a Toll Tag device having a modulated reflector. As the vehicle moves through the toll plaza, the RF reader illuminates passing vehicles with powerful RF energy. As the RF reader illuminates the vehicle, a modulated reflection signal is produced by the modulated reflector and is used to transmit the identity of the vehicle to the toll booth reader. In this manner, the positively-identified vehicle is charged a toll automatically without stopping and without any directed effort on the part of the driver.
Such systems which utilize frequencies typically of L-band or higher in order to exploit high data rates are currently under development. Common to these systems is the requirement of expensive, weatherproof reader equipment.
Accordingly, it is clear that modem specifications currently under consideration require costly equipment. The toll plazas are obviously not portable as extensive infrastructure is required. The large metal structures for holding the RF readers must be anchored to the ground in a way which will avoid collapse during earthquake. In addition, the RF energy produced by the RF reader may be powerful enough to raise concerns by certain segments of the public concerned with cancer health risks. Therefore, there is a need to overcome the limitations of cost created by: a need for extensive infrastructure, a need to overcome certain limitations imposed by nature, and a need to reduce the broadcast power of RF energy.